Natural gas, and mixtures of hydrocarbons that are volatile enough to make the mixture appear in gaseous form in room temperature, can constitute an advantageous alternative to fuel oil as the fuel of internal combustion engines. In sea-going vessels that use natural gas as fuel, the natural gas can be stored onboard in liquid form, giving rise to the commonly used acronym LNG (Liquefied Natural Gas). Natural gas can be kept in liquid form by maintaining its temperature below a boiling point, which is approximately −162 degrees centigrade. LNG can be stored at a pressure that is close to the atmospheric pressure, but large tanks used for storing LNG need to withstand significant hydrostatic pressures and a certain overpressure. For achieving good mechanical strength, LNG tanks can be constructed as cylindrical or spherical contain-ers. However, for practical reasons, large LNG tanks are sometimes designed as bilobe or multilobe tanks instead of cylindrical tanks. A bilobe tank includes two mating curved halves, for instance two spherical caps or two cylindrical segments. A multilobe tank includes at least three curved sections that are joined to each other. The sections can be partial cylinders or spheres.
Due to the low temperature desired for storing LNG, the dimensions of a tank that is in use and an empty tank that can be at a temperature of +30° C. can differ significantly from each other. This makes supporting of the LNG tanks challenging especially in ships, where it is desirable to firmly attach the tank to the hull of the ship.